ungrouped chondrite  DHO 535 

Stone chondrite 3.2/3.3 (S1,W5)


Description and references:

Many stones weighing 204 g were found in the Dhofar region of Oman. Mineralogy and classification (M. Ivanova, Vernad; L. Taylor, UTenn): the meteorite consists of chondrules, 0.08-3.2 mm in diameter, (0.86 mm in average) of different types, PO, POP, BO, RP, CC, and their fragments embedded in a fine-grained matrix. Chondrule/matrix ratio is 1.1. Olivine and low-Ca pyroxene have large compositional ranges: olivine has Fa1-50, CaO - 0.2 wt%; Al2O3 - 0.06 wt.%, Cr2O3 - 0.09 wt.%, PMD of Fa - 42%; low-Ca pyroxene is Wo2-3.5En53-95; chondrules contain glassy mesostasis. Accessory minerals include: pigeonite, chromite, troilite, rare hydroxides and essentially rare FeNi metal (Ni 5 wt%; Co 0.4 wt%). Thermoluminescence studies (A. I. Ivliev, Vernad) reveal petrological type 3.2/3.3. The meteorite is heavily weathered, some silicates are altered. Weathering grade is W5; shock stage is S1. Oxygen isotopic compositions (R. N. Clayton, UChi): d18O = +8.56; d17O = +4.96 are unusual for chondrites. Based on very low abundance of FeNi metal and hydroxides, and sizes of chondrules this unequilibrated ordinary chondrite can be preliminary classified as LL chondrite.